feat: add structured logging throughout audio pipeline

Add a lightweight log package (log/log.go) with debug/info/warn/error
levels. Wire it up via a -log flag (default: warn). Logging covers:

UDP transport:
- Socket open/failure, CryptSetup receipt, crypto initialization
- First UDP audio send confirmation
- UDP read errors and packet counts
- TCP fallback reason (no socket, waiting for crypto)

Audio pipeline:
- Source (mic) routine start with config details
- Audio stream start/end per remote user
- First audio stream creation for each user
- Packet loss detection with sequence gaps and PLC generation
- Decoder reset on sequence reordering

Usage: barnard -log=debug -server=mumble.example.com
Levels: debug, info, warn, error

main.go

@@ -15,6 +15,8 @@ import (
 	"strings"
 	"syscall"
 
+	barnlog "git.stormux.org/storm/barnard/log"
+
 	"git.stormux.org/storm/barnard/config"
 	"git.stormux.org/storm/barnard/gumble/go-openal/openal"
 	"git.stormux.org/storm/barnard/gumble/gumble"
@@ -114,9 +116,26 @@ func main() {
 	buffers := flag.Int("buffers", 16, "number of audio buffers to use")
 	profile := flag.Bool("profile", false, "add http server to serve profiles")
 	noiseSuppressionEnabled := flag.Bool("noise-suppression", false, "enable noise suppression for microphone input")
+	logLevel := flag.String("log", "warn", "log level: debug, info, warn, error")
 
 	flag.Parse()
 
+	// Set up logging
+	var level barnlog.Level
+	switch strings.ToLower(*logLevel) {
+	case "debug":
+		level = barnlog.LevelDebug
+	case "info":
+		level = barnlog.LevelInfo
+	case "warn":
+		level = barnlog.LevelWarn
+	case "error":
+		level = barnlog.LevelError
+	default:
+		level = barnlog.LevelWarn
+	}
+	barnlog.SetLogger(barnlog.NewWriterLogger(os.Stderr, level))
+
 	if *profile == true {
 		go func() {
 			log.Println(http.ListenAndServe("localhost:6060", nil))